This invention relates to apparatus and a method for stimulating salivation, and more particularly, to apparatus and a method for stimulating salivation by the application of electrical energy to nerves in the region of the oral cavity. Such stimulation, it has been found, can produce salivation by reflex action, by creating parasympathetic outflow to the salivary glands, parotid, submaxillary or sublingual.
When a patient is subjected to radiation treatment for carcinoma of the oral pharyngeal region, the radiation often produces as a side effect injury which results in the eventual necrosis of the salivary glands or the nerves associated with them. The injury may be unilateral or bilateral, depending upon the site of the application of the radiation and the dosage delivered. Loss of salivation results in drying of the epithelium of the oral cavity, attended by persistent and often debilitating pain and other symptoms.
The salivary glands can be stimulated to flow by electrically stimulating three nerve groups within the oral cavity and the surrounding region. These are: the maxillary nerve with its three divisions (anterior, middle and posterior), the mandibular nerve with its divisions and the lingual nerve. In general, the nerves of interest in connection with this invention have components which, when stimulated, produce reflex stimulation of the salivary glands.
The principal object of this invention is to provide a small, simple and effective apparatus to create an electrical stimulus which is capable of inducing salivation.
Another object of this invention is to provide a method for inducing salivation by means of electrical stimulation.
Other objects will appear hereinafter.
It has heretofore been proposed that electrical energy be applied in the oral cavity for a variety of medical reasons, but not for the purpose nor in the manner described herein. For example, in Russian Pat. No. 721,109, issued Aug. 15, 1977, a method is disclosed for treating inflammation of salivary glands by filling the salivary ducts with a liquid medication under pressure, and then using the liquid to carry out electrophoresis.
In German Offenlegungschrift No. 2740-188, published Mar. 8, 1979, a technique is disclosed for the application of an electrical stimulus to the gums to prevent, so the publication states, atrophy or bleeding of the gums and decay of the teeth.
In addition, it has heretofore been proposed (1) that electricity be applied to teeth or dental work to test neural response, (2) that electricity be applied to the gums to induce absorption of medicine by the gums, and (3) that pyorrhea be treated by the application of electricity. The above concepts, however, are not pertinent to the problem addressed by the present invention, or to its solution.
The above and other objects of this invention are realized, in a presently preferred form of the apparatus, by a stimulator which comprises a housing small enough to be comfortably received within the oral cavity of a user, the housing having an enclosure within which is housed a microcircuit and power supply capable of generating an electrical signal and a control switch. Associated with the housing, and electrically connected to the signal generator, are active and ground electrodes which apply the electrical signal to an area of the oral cavity which is determined by investigation to be neurally sensitive. Identification of the neurally sensitive area may be accomplished by applying to the oral cavity, on an exploratory basis, an electrical signal which simulates the salivation-inducting signal produced by the signal generator. One presently preferred technique for accomplishing this is the use of glove-mounted electrodes of the kind described in U.S. application Ser. No. 06/452,319, filed Dec. 22, 1982, now U.S. Pat. No. 4,510,939 for "MEANS FOR TRANSFERRING ELECTRICAL ENERGY TO AND FROM LIVING TISSUE" (assigned to the Assignee of the present application). It has been found that the application of a stimulus in the above manner induces salivation in those patients in whom pathosis is not so advanced or so profound that they cannot be helped by the present apparatus and method. In other words, if a patient has nerve function sufficient to increase salivation in response to the evaluative or diagnostic stimulus, that patient may be considered a logical candidate for the present apparatus and method. If a nerve has been so irradiated that it proves incapable of transmitting an impulse, then the glove and its associated electrode are placed in the region of the next potentially efficacious nerve. Thus, if the first-evaluated nerve was the maxillary, the next might be the mandibular nerve or, in turn, the lingual nerve on the tongue, until salivation is produced. If in fact salivation is not produced by stimulation on one side of the face (or medial plane), stimulus may be applied to the other side of the face until salivation is produced. Evaluation in this manner identifies a neurally sensitive "target", an area to which a stimulator in accordance with this invention may apply a stimulating signal.
In accordance with the present invention, therefore, at least one active electrode is juxtaposed as closely as possible to an area identified as neurally sensitive to electrical stimulation, and the stimulator may be maintained in place by a dental appliance clipped to the teeth or by association with a denture.
In its method aspect, the present invention involves the technique of identifying one or more neurally sensitive areas within the oral cavity; positioning with respect to those areas at least one active electrode capable to applying to those areas a stimulating signal; and generating a stimulating signal and applying the signal to sensitive area.
There are seen in the drawings forms of the invention which are presently preferred (and which represent the best mode contemplated for carrying th invention into effect), but it should be understood that the invention is not limited to the precise arrangements an instrumentalities shown or described.